Document Type : Structural Earthquake Engineering
Lawrence Livermore National Laboratory
University of California, Berkeley
In recent years computational simulation has taken an increased engineering importance in the seismic evaluation of critical structures. However, accurate nonlinear analyses of large suspension bridges continues to present earthquake engineers with a technically and computationally challenging problem. Application of general purpose nonlinear finite element software often results in computational models which are intractably large and computationally prohibitive. There are also specialized aspects to suspension bridges modeling, such as appropriate gravity initialization, that are not easily solved with general purpose computer programs. To address the simulation model challenges, a reduced order computational model has recently been developed for efficient nonlinear time history analysis. The model employs special element technologies tailored to suspension bridge applications and provides a hybrid implicit-explicit solution algorithm which can perform appropriate gravity initialization and adeptly handle extreme nonlinearties such as dynamic impact associated with pounding between bridge segments, foundation rocking or member buckling, and provide a framework which is readily migrated to a massively parallel compute environment. The computational model is described and a sample application is presented for the near-field seismic response of the San Francisco-Oakland Bay Bridge Western Crossing (USA).